June 20, 2006

Securities and Exchange Commission
100 F. Street, N.E.
Washington, D.C. 20549-7010

Re:  AAON, Inc.
     Form 10-K for fiscal year Ended December 31, 2005
     Forms 10-Q for the Fiscal Quarter Ended March 31, 2006
     File No. 000-18953

Attention:  Ms. Nili N. Shah
            Branch Chief

Dear Ms. Shah,

This letter is in response to your letter dated May 25, 2006.

Form 10-K for Fiscal Year Ended December 31, 2005
- -------------------------------------------------

Note 1. Business, Summary of Significant Accounting Policies and Other
        Financial Data

Warranties, page 35
- -------------------

1. Response: In future filings of Form 10-K, we will separately present the
amount of the provision recorded that represents the aggregate changes in the
warranty liability for accruals related to preexisting warranties (including
adjustments related to changes in estimates) for each of the years presented in
accordance with the paragraph 14b of FIN 45. The presentation of the rollforward
of warranty activity will be as follows:


                                                    2004       2005       2006
                                                    ----       ----       ----
   Balance, beginning of period
   Payments made
   Warranties issued
   Changes related to preexisting warranties
   Balance, end of period


If such information is required to be presented on an interim basis pursuant to
Rule 10-01(a)(5) of Regulation S-X, the Company will provide the required
disclosure in interim financial statements to be filed on Form 10-Q.

                                      (1)


Segments, page 38
- -----------------

2. Response: The Company manufactures and sells air-conditioning and heating
equipment. The Company has three operating divisions: AAON, Inc. ("AAON"), AAON
Coil Products, Inc. ("ACP"), and AAON Canada ("Canada"). AAON and Canada
manufacture heating, ventilation and air-conditioning (HVAC) units that are the
same type of product, can be interchangeable and often sold to the customer as
one product. A major part of the operations at the ACP plant are coils, which
are assembled with other parts in comprising a finished HVAC unit. The
production of coils is viewed simply as part of the process of making a finished
HVAC unit, similar to the fabrication of sheet metal parts used in the
production of final HVAC units.

We consider each of the three operating divisions "operating segments" as
defined in paragraph 10 of Statement of Financial Accounting Standard No. 131,
"Disclosures about Segments of an Enterprise and Related Information"(SFAS 131).
However, we believe it is appropriate to aggregate the three operating segments
for reporting purposes in accordance with the provisions of paragraph 17 of SFAS
131. Paragraph 17 of SFAS 131 allows aggregation of operating segments if the
aggregation is consistent with the objective and basic principles of SFAS 131,
if the segments have similar economic characteristics, and if the segments are
similar in each of the following areas: (1) the nature of the products and
services, (2) the nature of the production process, (3) the type of class of
customer for the products, (4) the methods used to distribute the products, and
(5) if applicable, the nature of the regulatory environment.

We believe that the result of the referenced considerations are consistent and
are indicative of the same economic focus for AAON, ACP and Canada. The areas
listed in (1)-(5) above are similar for each of the three operating segments
because the products produced at the three segments are generally
interchangeable or used in the manufacturing process at one of the other
operating segments; the production process is similar in that similar raw
materials, fabrication methods, manufacturing processes, and the amount and
nature of the direct labor costs are similar across the segments; all segments
sell to the same customers using the same sales force; the distribution methods
are the same (sold to resellers or directly to end customers); and there are no
significant differences in the regulatory environments each segment operates in.

Pursuant to your request for historical operating data for each of our operating
segments, we submit the following analysis:



- ------------------------- ---------------------------------- ---------------------------------- ---------------------
                                        2005                               2004                         2003
- ------------------------- ---------------------------------- ---------------------------------- ---------------------
                            AAON        ACP       CANADA       AAON        ACP       CANADA       AAON        ACP
- ------------------------- ---------- ---------- ------------ ---------- ---------- ------------ ---------- ----------
                                                                                      
Revenues                    166,638     35,742      11,208     162,046     34,074       3,326     142,594     26,249
- ------------------------- ---------- ---------- ------------ ---------- ---------- ------------ ---------- ----------
Gross profits                30,144      7,064      (1,580)     24,970      2,872        (630)     31,969      3,820
- ------------------------- ---------- ---------- ------------ ---------- ---------- ------------ ---------- ----------
Gross profit margins         18.09%     19.76%     (11.71%)     15.41%      8.43%     (14.94%)     22.42%     14.55%
- ------------------------- ---------- ---------- ------------ ---------- ---------- ------------ ---------- ----------
Operating profits            16,637      3,940      (2,697)     12,216        612        (926)     18,707      2,181
- ------------------------- ---------- ---------- ------------ ---------- ---------- ------------ ---------- ----------
Operating profit margins      9.98%     11.02%     (19.99%)      7.54%      1.80%     (21.96%)     13.12%      8.31%
- ------------------------- ---------- ---------- ------------ ---------- ---------- ------------ ---------- ----------


                                      (2)


In determining whether it would be appropriate to aggregate the three operating
segments into one reportable segment, we considered whether the similarity of
historical operating results met the requirement that the aggregated operating
segments have similar economic characteristics. We considered the following:

         ACP - ACP's primary purpose is to provide component parts for completed
         HVAC units produced at AAON and Canada. To that extent, ACP's business
         is simply an extension of the AAON and Canada's operating segments. If
         ACP has additional manufacturing capacity beyond the capacity required
         to provide component parts for completed HVAC units produced at AAON
         and Canada, then ACP will sell parts to third party customers. Those
         outside sales have averaged only approximately 20-25% of ACP's total
         sales for each of the three years in the period ended December 31,
         2005. If AAON's or Canada's volume increased to the extent that ACP
         would no longer be able to fulfill orders from outside customers and
         meet the production requirements for AAON and Canada, then ACP would
         reduce the sales to outside parties and focus only on supplying parts
         to AAON and Canada.

         Additionally, we did not consider it appropriate to rely solely on the
         operating statistics of ACP when determining the appropriateness of
         combining the ACP operating segment with the other two operating
         segments of the Company as the pricing on inter-company sales is
         established by the chief operating decision maker of the Company. The
         total operating results of the ACP division are impacted primarily on
         the prices that the chief operating decision maker sets for
         inter-company sales.

         Therefore, we considered it more appropriate to rely on the
         similarities of the nature of the products sold, the nature of the
         production process, the type of class of customer for the products, the
         methods used to distribute the products and the similarity of the
         regulatory environments in determining the appropriateness of combining
         the ACP operating segment with the other operating segments to form one
         reportable segment.

         Canada - Canada was acquired in May, 2004 and has undergone significant
         changes since the acquisition. The Company has done extensive
         programming to accommodate the Canadian and U.S. Dollar conversion of
         reports, a manufacturing standard cost system has been implemented, a
         formalized system to schedule jobs into production, and production line
         enhancements. The Company has begun, but has not yet completed, the
         integration of certain pricing methodologies utilized by AAON and ACP
         due to the backlog of existing contracts at the acquisition date and
         the time spent by management integrating the business. Although
         Canada's gross margins and gross margin percentage were significantly
         lower than AAON's and ACP's during 2004 and 2005, management expects
         the margins to be consistent with AAON and ACP's margins in the future
         and that the three operating segments have essentially the same future
         prospects once the appropriate pricing methodologies are fully
         implemented. Our long term strategic plan predicts that Canada's
         margins will be consistent with our expectations about future margins
         at AAON and ACP. The above table shows improvements in Canada's
         operating results during 2005 as compared to 2004 and we continue to
         see improvements in Canada's operating results during the first part of
         2006.

                                      (3)


         However, because our plan to improve Canada's operating results had not
         been completed by the end of 2005, we believed it was appropriate to
         highlight disclosure of Canada's results of operations in the
         management discussion and analysis section of our 10-K and in quarterly
         press releases issued during 2005 to highlight the impact the recent
         acquisition of Canada had on the operating results of the Company.

         We will continue monitoring the results of Canada to determine that our
         expectation that the Canada operating segment display similar future
         economic characteristics as our other operating segments is an
         appropriate assumption. If our expectation changes, we will present
         Canada as a separate reporting segment in the future.

With respect to the various products offered by the three operating segments,
the Company manufactures various sizes of HVAC equipment with various features.
For tracking and monitoring purposes, the various sizes of equipment are
assigned unique product numbers. However, the products are not dissimilar and
are manufactured, sold and distributed in similar manners and to the same
customers. Additionally, each product has a similar ratio of planned material,
labor, and overhead costs and the actual amounts of those costs tend to vary
only with the size of the product ordered. In addition, AAON, ACP, and Canada
each have a separate senior management person that oversees management, sales,
and engineering performance for each location. We considered all of the above
factors, including the nature of the similarities of the product lines, when
determining our operating segments and determined that the three operating
divisions described above were more consistent with the objectives and basic
principles of SFAS 131 related to operating segments rather than our various
product lines.

Norman H. Asbjornson, President and Chief Executive Officer, is the chief
operating decision maker as defined by SFAS No. 131. In that role, Mr.
Asbjornson regularly reviews the results of operations of each operating
segment, gross margin reports, and consolidated financial information. As noted
below, the type of information reviewed and used by Mr. Asbjornson in evaluating
segment performance and determining appropriate resource allocations is being
provided under separate cover.

In connection with responding to your comments, the Company acknowledges that:

     o    The  Company is  responsible  for the  adequacy  and  accuracy  of the
          disclosure in the filing;

     o    Staff  comments or changes to disclosure in response to staff comments
          do not foreclose the Commission from taking any action with respect to
          the filing; and

     o    The  Company  may  not  assert  staff  comments  as a  defense  in any
          proceeding initiated by the Commission or any person under the federal
          securities laws of the United States.

As requested, we are submitting December 31, 2005, and March 31, 2006 internal
gross profit reports and financial statements for AAON, ACP and Canada that are
regularly provided to the Chief Executive Officer. These reports are hard copy
reports that cannot be reproduced and downloaded into a document format that can
be Edgarized, so we are sending hard copy reports via overnight delivery service
to the attention of Melissa N. Rocha, Division of Corporate Finance.

                                      (4)


If the staff has any further comments or questions, please feel free to contact
the undersigned. We would further ask that you provide a copy of any additional
comments or questions to our General Counsel, John B. Johnson, Esq., at Johnson,
Jones, Dornblaser, Coffman & Shorb, Suite 2200, Bank of America Center, Tulsa,
Oklahoma, 74119.

Sincerely,


/s/ Kathy I. Sheffield
- ----------------------
Kathy I. Sheffield
Vice President/Treasurer



                                      (5)